A young customer eats a cupcake bought from a truck in Chicago. Sales from food trucks are expected to quadruple by 2017, to $2.7 billion.

Sitthixay Ditthavong/AP/File

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Nothing beats escaping the office for a summer lunch outside. Maybe you were organized enough to pack your lunch. Even better: Your favorite restaurant rolls up to the curb and hands you a paper carton of teriyaki chicken nestled on a bed of steaming rice.

From grilled cheese to cupcakes to the latest fusion cuisines, a growing number of food trucks are roving city streets as patrons – and now restaurants – discover the ease, ingenuity, and affordability of sidewalk meals.

Street vendors – from quilted aluminum vending trucks at construction sites to ice cream trucks selling to children – have been around for decades. But enterprising restaurateurs have updated that model with splashy logos on delivery trucks retrofitted with kitchens. Through social media sites, patrons can track down their favorite trucks whenever the hankering for a hot fish taco or falafel wrap strikes.

With low overhead, quick service, and the flexibility to adapt to trends, food trucks are the fastest-growing dining industry in the United States. Over the past five years, the sector has grown an average 8.4 percent a year, according to industry analyst IBISWorld in Los Angeles. Food truck revenue, which last year reached $650 million, is expected to quadruple to $2.7 billion by 2017, according to Emergent Research, a small-business research and consulting firm based in Lafayette, Calif.

"We like to try different things [on the menu] and have fun, and the food truck allowed this," says Sienam Lulla of Momos & Buns. The bright red and orange truck offered piping-hot fusion Chinese food at a recent Boston food truck competition among nearly 20 Boston and New York City vendors. Ms. Lulla, who also owns two restaurants with her husband, says that once you go corporate, you get locked into doing menus a certain way. With a food truck, "you get instant feedback from customers."

The modern gourmet food truck movement is often traced to Roy Choi, who launched his Kogi BBQ food trucks selling fusion Korean tacos in Los Angeles in 2008. In his first year, he raked in $2 million selling $2 tacos. The trend quickly traveled up the coast to San Francisco, Seattle, and beyond. By 2010, gourmet food trucks were spotted in most major cities; "The Great Food Truck Race" was a show on the Food Network; the prestigious Zagat guide announced it would begin reviews.

Many restaurant owners see an opportunity to expand their customer base by launching their own trucks. A 2012 poll found that 22 percent of "fast casual" and 13 percent of "quick service" and "family-dining operators" are considering adding a food truck, according to the National Restaurant Association, a Washington-based trade group.

The phenomenon has stirred controversy. Some bricks-and-mortar restaurants have appealed to zoning boards to slow the spread of the trucks, which don't pay real estate taxes or rent, but do hog parking spots, steal customers, and have noisy generators. In Des Moines, Iowa, the city council implemented regulations that would require vendors to set up in the same place every day and provide a restroom within 500 feet. Nick Mallia, the catering event manager for the Paris Creperie, a cafe in Brookline, Mass., says getting his restaurant's peach-colored food truck up and running involved a "struggle to get the approval from selectmen," who were concerned about its effect on traffic and local businesses.

But in some smaller US cities, such as Champaign, Ill., and Lexington, Ky., officials are gradually opening up zoning laws to allow more food trucks. Cities with established rosters of dozens of food trucks are using them to draw tourists into downtowns. For example, some 31,000 people in Oceanport, N.J., endured a drizzly weekend in May to sample offerings during the Jersey Shore Food Truck Wars.

Some food truck entrepreneurs have found such a successful following that they have opened bricks-and-mortar restaurants under the same name. The owners of Mei Mei Street Kitchen, a Chinese-American food truck run year-round by siblings in Boston, plan to open a restaurant near the Boston University campus by late summer.

The new place "will reflect the food truck spirit," says Mei Li, a founding sister, including an open kitchen and walk-up counter – only inside, with no idling generators or winter snowstorms.